Leptin & Leptin Resistance

What is leptin?

Leptin is a hormone your adipose tissue (body fat) releases that helps your body maintain your normal weight on a long-term basis. It does this by regulating hunger by providing the sensation of satiety (feeling full).

Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, muscles and other tissues. These signals tell your body what to do and when to do it.

Scientists discovered leptin in 1994, so they’re still studying it to understand all of its effects.

What is the function of leptin?

Leptin’s main function is to help regulate the long-term balance between your body’s food intake and energy use (expenditure). Leptin helps inhibit (prevent) hunger and regulate energy balance so that your body doesn’t trigger a hunger response when it doesn’t need energy (calories).

Leptin mainly acts on your brainstem and hypothalamus to regulate hunger and energy balance, though you have leptin receptors in other areas of your body.

Leptin doesn’t affect your hunger levels and food intake from meal to meal but rather acts to alter food intake and control energy expenditure over a longer period of time to help maintain your normal weight.

Leptin has a more profound effect when you lose weight. As your body fat (adipose tissue) decreases, your leptin levels decrease, which signals your body to think that it’s starving. This stimulates intense hunger and appetite and can lead to increased food consumption.

Scientists are still studying leptin, and they believe it also affects your metabolism, endocrine system regulation and immune system function.

How are leptin levels controlled?

Your white adipose tissue (body fat) makes and releases leptin. White adipose tissue is the main type of fat in your body. It’s located beneath your skin, around internal organs, in the middle cavity of your bones. White adipose tissue serves as cushioning for various parts of your body.

The amount of leptin in your blood is directly proportional to the amount of adipose tissue your body has. In other words, the less body fat, the less leptin you have, and the more body fat, the more leptin you have.

Leptin levels increase if your fat mass increases over time, and they decrease your fat mass decreases over time.

What test measures leptin levels?

A blood test can check the amount of leptin in a blood sample taken from a vein in your arm.

Healthcare providers don’t routinely test for leptin levels, and the test isn’t offered by all laboratories. Providers typically only consider ordering leptin tests if someone has obesity and has persistent hunger, or if a young child has class III obesity.

What are normal leptin levels?

Normal value ranges for leptin levels may vary slightly among different laboratories. Be sure to look at the range of normal values listed on your laboratory report or ask your healthcare provider if you have questions about your results.

In general, normal ranges for leptin levels include:

• Adults assigned female at birth: 0.5 - 15.2 nanograms per milliliter (ng/mL).
• Adults assigned male at birth: 0.5 - 12.5 ng/mL.

What happens when leptin levels are too high?

Since the amount of leptin in your blood is directly proportional to the amount of adipose tissue (body fat), having obesity results in high levels of leptin (hyperleptinemia). This can cause a lack of sensitivity to leptin, a condition known as leptin resistance.

Other conditions associated with hyperleptinemia include:

• Nonalcoholic fatty liver disease.
• Rabson–Mendenhall syndrome.
• Neurodegenerative disorders.
• Depression.
• Food addiction.

What is leptin resistance?

If you have leptin resistance, your brain doesn’t respond as it normally would to leptin. Since it’s constantly stimulated by leptin, you don’t get the sensation of feeling full or satiated. This causes you to eat more even though your body has enough fat stores.

The seeming lack of leptin in leptin resistance also causes your body to enter starvation mode. In an effort to save energy, your brain decreases your energy levels and makes you use fewer calories at rest.

Leptin resistance thus further contributes to obesity and causes additional weight gain in the form of fat storage due to stimulating hunger and decreasing metabolism.

Scientists are currently working on developing medications that can treat leptin resistance.

What are the symptoms of leptin resistance?

Leptin resistance results in a decrease in the ability of leptin to suppress appetite or increase your body’s energy use. Because of this, the main symptoms of leptin resistance are constantly feeling hungry and increased food intake despite having adequate or excess amounts of body fat.

However, several other factors and conditions can contribute to these symptoms — not just leptin resistance. Scientists are still learning about leptin and may later discover other symptoms of leptin resistance.

What happens when leptin levels are too low?

It’s very rare to have lower-than-normal leptin levels (hypoleptinemia). The main condition associated with low leptin levels is called congenital leptin deficiency, which is a genetic condition you’re born with that prevents your adipose tissue from producing leptin.

Without leptin, your body thinks it has no body fat, which then signals intense, uncontrolled hunger and food consumption. Because of this, congenital leptin deficiency results in class III obesity in children and delayed puberty. It’s also associated with the following conditions:

• Frequent bacterial infections.
• Hyperinsulinemia (excess insulin production).
• Fatty liver disease.
• Dyslipidemia (an imbalance of lipids, including cholesterol and triglycerides).
• Hypogonadotropic hypogonadism (low sex hormone levels).

How do I raise my leptin levels?

Unfortunately, there’s not much you can do to raise your leptin levels to decrease hunger and appetite, since your leptin levels are directly related to how much adipose tissue your body has.

One study found that sleep-deprived people had high levels of ghrelin, a hormone that signals hunger, and lower levels of leptin. Getting appropriate amounts of quality sleep is important for several reasons, so, in any case, it’s beneficial to your overall health.

Scientists are also looking at the relationship between leptin and triglycerides, a type of fat also known as lipids. Some studies have revealed that high triglycerides seem to impact the way leptin works, but these studies are controversial. While some scientists think a diet that’s designed to lower triglycerides could help boost your leptin levels, other scientists disagree.

What foods are high in leptin?

Since leptin is a hormone your body makes and not a nutrient (like vitamin C or protein), no foods contain leptin.

A note from Cleveland Clinic

Since leptin is a relatively new discovery, scientists are still working to learn more about it, including how it affects obesity and weight loss. Leptin’s role in triggering your body’s starvation mode when your body fat decreases can make it difficult to lose weight. If you’re concerned with your body weight or want guidance on how to lose weight in a healthy way, talk to your healthcare provider or consider seeing an endocrinologist who specializes in hormones and can offer weight management programs.